Method and Process for Acidic Recycling of Protein Waste

ABSTRACT

A method for recycling protein waste and producing an edible product for animal consumption comprises grinding animal carcasses or parts thereof and thereafter acidifying the waste. The acidified waste may then be emulsified, followed by a heat shock and then fed to animals. Alternatively, a second emulsification may be employed prior to being used for animal consumption. The emulsified products may be provided to animals as a liquid, or dried to a paste prior to use.

PRIORITY STATEMENT

This is a Continuation-In-Part of U.S. application Ser. No. 13/563,214filed Jul. 31, 2012 which is a continuation in part of U.S. applicationSer. No. 12/925,359 filed on Oct. 20, 2010 (which issued as U.S. Pat.No. 9,161,554 on Oct. 20, 2015), which is a Continuation of U.S.application Ser. No. 11/706,123 filed Feb. 14, 2007 (which issued asU.S. Pat. No. 7,851,210 on Dec. 14, 2010), which is aContinuation-In-Part of U.S. application Ser. No. 10/607,691 filed Jun.30, 2003 (which issued as U.S. Pat. No. 7,226,778 on Jun. 5, 2007), theentire contents of each application and patent being incorporated hereinby reference.

BACKGROUND

1. Field

Example embodiments relate, in general, to apparatuses and processes fornaturally recycling protein waste into feed and, more specifically, toapparatuses and processes for enzymatic digestion or acidic digestion,emulsification and, optionally, drying of protein waste includingfeathers for use as or in animal feed.

2. Description of the Related Art

A mass of waste is accumulated on a regular basis in such operations aspoultry production facilities. Protein waste such as carcasses from deador recently euthanized birds from poultry production facilities poseproblems for disposal. Such problems include odor and generation ofbacteria in the building or anywhere such waste is left for a period oftime. Carcasses are currently disposed of in many ways including landfilling and burning, each of which comprise attendant problems.

Natural gas production from waste materials is also known in the art.Such processes typically also result in a byproduct which is used asanimal feed or fertilizer.

Some facilities process the protein waste to produce a component foranimal feed. These plants often are not designed to provide a mostlyclosed system. Consequently, air, moisture, and other contaminants mayenter creating an environment where microorganisms can multiply anddestroy the quality or usefulness of the processed protein waste.

And, although there may be processing plants from which protein wastemay be acceptably disposed and recycled, there is not an efficient wayto remove the waste from the site to the processing plant in such timeand condition as necessary for efficient processing. The timing of suchremoval is essential to managing toxicity and odors; on the other hand,it is typically not feasible for each animal production plant to alsooperate a processing plant for its protein waste.

Animal feed requires a protein component. In addition to the carcasseswhich can be processed for protein recovery, feathers are inexpensiveand also high in protein, however, feathers are difficult for animals todigest. And, although there are processes known for forming feathermeal, often these processes require steam which, if too hot, willdenature the proteins in the feathers and reduce their nutritionalvalues. Alternatively, it is also known that certain bacterial strainsproduce keritinase which is an enzyme capable of degrading feathers andthat, properly employed, such degradation can result in material thatcan be used in animal feeds. See U.S. Pat. Nos. 4,908,220; 4,959,311.

Another approach for recycling protein is known in the art and providesmeans to grind swine or poultry carcasses and then mix it withingredients that will facilitate fermentation of the waste. See U.S.Pat. No. 5,713,788. The invention disclosed therein provides a specificgrinding mechanism which includes a grinding drum with a helical grooveon its outer surface in which a length of chainsaw chain, teeth sideout, is positioned. This invention does not include a way tore-circulate and thoroughly mix the ground protein and catalyst but,instead, depends on a metered application of catalyst to the groundprotein waste as it moves past the grinder wherein the metering of thecatalyst is triggered by the load on the grinder. This is deficient inthat no additional mixing of the ground protein and catalyst iscontemplated such that there is substantial risk that it will not beappropriately mixed and the catalytic action will be hampered.

What was needed was an approach for animal production facilities toefficiently and timely dispose of animal waste in the form of carcassesin a way that is non-toxic and odor free. In addition, the approachshould be affordable for the animal production facilities and theresulting recycled product must be usable. Preferably, a mostly closedsystem should be used to eliminate environmental contaminants and toprovide avenues for recycling by-products. Finally, for any disposal offeathered animals, the system must provide a method of breaking down notonly softer protein sources, but also feathers and in a manner that doesnot denature or destroy the food value of the proteins.

Example embodiments provide a system wherein animal carcasses such aspoultry carcasses from dead or recently euthanized poultry are processedin such a way that a portion of the system may be mobile and can betaken from one animal production facility to another or simplypositioned at one facility until it reaches capacity.

Example embodiments also provide a protein processing system which iscapable of degrading feathers without destroying their food value.

Example embodiments also provide a way for many different and maybedistant animal production facilities to have routine access to aprocessing facility.

Example embodiments also provide a means for recycling and breaking downthe carcasses comprising animal protein wastes and to recycleby-products of the process.

Example embodiments also provide an apparatus with mixing and grindingcapabilities associated with one another in a manner that results in amostly closed system which may be an efficient process for digesting,emulsifying and drying the recycled protein waste while also providing ameans for recycling other byproducts such as water and for minimizinggrowth of damaging microorganisms. Example embodiments provide a processfor grinding proteinaceous material with acid or to which acid is addedto be used as an acidic digest, along with enzymes, generally proteases,to from an acidified digest medium. This medium is of acidic pH. Themedium may be heat shocked and, optionally, emulsified. Additionalproteinaceous material may be added to this medium on farm to form astable product that may be stored for up to about 25 days. The stableproduct may be packaged; emulsified prior to packaging; and/or dried,with or without a carrier that may include yeast to result in aprotein-containing product that may be fed to animals. Some embodimentsthat include grinding acidified proteinaceous material employ theaforementioned heat shock, and/or a second emulsification step, othersdo not.

Example embodiments provide a process that may be performed withoutsodium bisulfite: sodium bisulfite is known to scavenge B vitamins and Bcomplex.

Example embodiments include the use of phosphoric acid. In that case,the acid acidifies and frees up phosphate which has benefits to animalhealth, particularly relative to bone health. Other acids may beemployed that may not result in contribution of phosphate to the endproduct but still produce a useful product.

Example embodiments may also provide an apparatus for recycling animalprotein that produces fuel from the digesting or fermentation of animalprotein waste.

Example embodiments may also provide an apparatus for animal proteinrecycling that produces fuel and uses the produced fuel to powerportions of the apparatus.

SUMMARY

Example embodiments provide an apparatus and several processes fornaturally recycling poultry carcasses or parts thereof for use as anutritional supplement for animals. The apparatus may have four modules:(1) a pH adjustable enzymatic digest medium mixing assembly, (2) amobile grinding assembly which may be mounted on a truck trailer; (3) adigesting and emulsifying assembly which may include a heated tank andseparator or alternatively a fermentation assembly; and (4) a dryingsystem.

An enzymatic digest medium of example embodiments may includeprotease/keritinase, inedible egg or a waste fluid that includes proteinwith or without fat, water as needed, and a preservative. The amount ofpreservative to be added to the medium may be determined by a circuitusing data from a load sensor on the grinding means to control avariable frequency drive is controlled according to the load and maycontrol the speed of a preservative pump. The digest and emulsifyingassembly may be equipped with a pH probe and monitor which may triggerthe addition of an acidic solution as needed to adjust a pH of theenzymatic digest.

In an alternative method, the recycling may be accomplished via acidicdigestion. A ground protein material which may comprise yeast or anotherprotein source may be mixed with an acid or acids, and at least oneenzyme where one of the enzymes comprises a protease, to form an acidicdigest medium. The enzymes employed may comprise a mixture of proteases,a single protease, or a mixture of enzymes that includes at least one ormore proteases. The preferred proteases of the present invention arethose that tolerate and remain active at acidic pH. Most preferredpossible proteases tolerate and remain active at pH between about 2.5and about 4.0.

The acidic digest medium may include yeast as a protein source, enzymethat includes at least one protease, optionally potassium sorbate,optionally antioxidants, and is acidified by adding an acid or acidssuch as, but not limited to, phosphoric acid to pH around 2. Thismixture comprises the acidic digest medium which remains stable for upto about 25 days.

The acidic digest medium is preferably subjected to a heat shock step,preferably raising the temperature to about 160 degrees F. prior tostorage. The components of the acidic digest medium may be emulsifiedtogether. The emulsification may occur prior to any heat shock step, ifone is employed. Alternatively, the acidic digest medium is notsubjected to a heat shock step but is simply emulsified. In yet anotherversion of the inventive method and system, the acidic digest medium isemulsified prior to being subjected to a heat shock step, which may ormay not be followed by a second emulsification step.

The protein material may comprise poultry parts or other animal partsand may be combined with acid and yeast, enzyme, potassium sorbate,antioxidants during the grinding step or added after, or both before andafter, to form the digest. Thereafter, the acidic digest medium may beemployed to digest proteinaceous materials such as poultry, on farm.Specifically, poultry carcasses may be ground with the acidic digestmedium and, thereafter, form a digest. The pH of the digest is typicallyaround about 3.5 but may be between about 2.5 and 4, and the digest maybe stably stored for up to about 25 days. Thereafter, the digest(wherein the protein materials have been mostly liquefied) may be driedor may be combined with a carrier and then dried, or may be employed inits substantially liquid state.

The mobile grinding assembly may be moved from one animal productionfacility to another or may remain at one facility. The mobile grindingassembly of example embodiments may be mounted on a trailer and mayinclude a holding tank for the enzymatic (or acidic) digest medium and aconveyor for loading carcasses into a grinder. The remainder of thegrinding assembly may be a closed system. Once through the grinder, theground carcasses or portions or parts thereof may be pumped into astorage tank with the enzymatic digest medium to produce a proteinsolubles mixture.

In another embodiment ground carcasses may be combined with acid to forma second type of digest. The ground proteinaceous material is acidifiedto pH between about 2.5 and about 4.0, optionally followed by a heatshock step of about 160 F. The heat shock may be preceded or followed byan emulsification step in some embodiments the heat shock step is bothpreceded by a first emulsification step and followed by a secondemulsification step. This acidic digest mixture may then be recirculatedthrough a chopper pump with additional carcass parts for a few minutesto further reduce particle size of the ground protein waste and assureadequate mixing of the acidic or enzymatic digest and the proteins toform a protein solubles mixture, and then pumped into a tanker truck fortransport. Multiple batches of the protein solubles mixture may begenerated so that the storage tanks may be filled and emptied as manytimes as necessary until all the waste has been disposed. Then, themobile grinding assembly can be moved to another location or it cansimply remain until it is needed again.

The protein solubles mixture created by the mobile grinding assembly maythen be moved to a centralized and stationary processing plant andtransferred from the tanker truck to the digesting and emulsifyingassembly. An enzyme digest of the present invention in the proteinsolubles mixture may work best between about 100 and 130 degreesFahrenheit while other enzyme digests disclosed work best under 125degrees Fahrenheit. When employing the acidic method, temperaturesbetween about 90 and about 120 F suffice. Therefore, the digesting andemulsifying assembly may heat the mixture if needed and onlyperiodically recirculate it until the enzymatic digest (or acidicdigest) has altered the protein solubles to a mostly liquid state.Optionally, the acidic digest process may comprise a mincing step tofurther and faster digestion. Thereafter, the acidic digest may bestored for up to 25 days. For embodiments that include digestion ofparts that include fats, or for enzyme or acidic digest mediums thatinclude fat content, it may be preferred to emulsify the digestedprotein solubles to completely disperse the fats and proteins.Optionally, the acidified proteins may be emulsified before a heat shockstep comprising temperature of 150 F-170 F, more preferably around 160 Ffor a short time, and thereafter stored and/or emulsified a second time.For example purposes only, the first emulsification may employ a 5 mmplate whereas the second emulsification may employ a 3 mm plate. Thedigested and emulsified proteins resulting from either the enzymatic oracidic digest medium may then be pumped into a separator tank and thebottom layer of water may be drained off periodically, leaving theemulsified proteins. The water layer may then be recycled back to theportion of the system where the enzymatic digest is made. For the acidicdigest, remaining emulsified proteins may either be used in their liquidstate as an animal food product or may be transferred to a dryer or,alternatively, may be blended with other ingredients, then extruded anddried to form a non-liquid animal food product.

In example embodiments where it is desirable to remove fats, the fatsmay be collected from the digest and emulsification assembly via acloseable connection and a first fats tank. In the enzymatic version ofthe invention, fats may be separated from the protein solubles mixtureby addition of acid from an acid tank via a pump. A valve on therecirculation means may close to allow transfer of fats from the digesttank through an open closeable connection. Fats in the first fats tankmay be separated from water in a centrifuge and stored in a second fatstank. The water collected may be recycled back into the digester tank.

In alternative to the digest and emulsification assembly, the apparatusmay include a fermentation assembly. In the fermentation assembly theprotein solubles mixture is broken-down by bacteria which produces gas.Gas may be collected by a piping and compressed by a compressor into apressure tank. Check valves along the piping prevent backflow of gas.The compressor may be controlled by a pressure sensor on thefermentation tank.

The dryer system may use a carrier for surface absorption of moisture,extrusion, air flow, and heat to accomplish the removal of moisture. Acarrier such as cereal, soybean meal, corn or wheat mids may be fedthrough a volumetric feeder to a mill where it may be finely ground toprovide ample surface area for absorption. The carrier may then beconveyed to a mixer where it may be mixed with the emulsified proteins(which are the result of either the acidic method or enzymatic method)until a dough like consistency is reached. At this point, the dough isfed into an extruder to remove additional moisture and to extrude doughpellet-like pieces which may then be moved by oscillating belt to thedrying apparatus.

The drying apparatus may include a dryer bed which, in exampleembodiments, may be a conveyor belt enclosed in a housing. The housingmay alternate air flow direction and have heat zones for removing yetmore moisture content and a cooling zone to return the pellet-likepieces to near room temperature. The pellet-like pieces may then bemoved progressively through the air flow, the heat zones and the coolingzone by the conveyor. In example embodiments, the pellet-like pieces maybe sized and then run over a vibrating screen to separate thenon-uniform sized pieces. Finally, the appropriately and uniformly sizedpellet-like pieces may be packaged.

Other objects, features, and advantages of example embodiments will bereadily appreciated from the following description. The descriptionmakes reference to the accompanying drawings, which are provided forillustration of example embodiments. However, example embodiments do notrepresent the full scope of the invention. The subject matter which theinventor does regard as his invention is particularly pointed out anddistinctly claimed in the claims at the conclusion of thisspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a mobile grinding assembly portion inaccordance with example embodiments;

FIG. 2 is a diagram showing an acidic digest mixing assembly portion inaccordance with example embodiments;

FIG. 3 is a side view of a mobile grinding assembly portion inaccordance with example embodiments;

FIG. 4 is an enlarged plan view of the mobile grinding assembly of FIG.3;

FIG. 5 is a side view of a digesting and emulsifying assembly portion inaccordance with example embodiments;

FIG. 6 is a side view of a fermentation assembly portion in accordancewith example embodiments;

FIG. 7 is a block diagram showing the components of a dough mixingapparatus and an extruder of a drying system portion in accordance withexample embodiments;

FIG. 8 is a block diagram of a drying apparatus of the drying systemportion in accordance with example embodiments;

FIG. 9 is a flow diagram showing the steps for the process for naturalrecycling of protein waste in accordance with example embodiments;

FIG. 10 is a diagram showing an acidic digest mixing assembly portion inaccordance with example embodiments; and

FIG. 11 is a plan view of a mixing device and a grinding assembly inaccordance with example embodiments.

DETAILED DESCRIPTION

Example embodiments provide an apparatus and process usable for, amongstother things, naturally recycling protein waste. In example embodiments,the apparatus and process for naturally recycling protein waste mayinclude an acidic digest mixing assembly shown generally as 15 in FIG.2, a mobile grinding assembly shown generally as 40 in FIGS. 3 and 4, adigesting and emulsifying assembly shown generally as 100 in FIG. 5 or afermentation assembly shown generally as 200 in FIG. 6, and a dryingsystem shown generally as 126 in FIGS. 7 and 8. These components may allbe present on a movable platform or separated; for example, the mobilegrinding assembly may be movable while the acidic digest mixing assembly15 is stationary.

In example embodiments, the process, as is shown in the flow chartdepicted in FIG. 9, may include an acidic medium 112 of a particular pHlevel that may be prepared and stored until such time as it is needed.The acidic medium 112 of example embodiments may include acid 114A,inedible egg 16, a preservative or preservatives 18, and water. Theacidic medium 112 may include any of several acids including phosphoricacid, and may include yeast as a protein source, potassium sorbate,antioxidants as preservatives 18. The preservative 18 may be sufficed bythe acid which may restrict multiplication of bacteria or microorganismswhich could adversely affect the end product. Although inedible egg 16is a logical choice when the process is used in conjunction with poultryproduction, other fluid wastes such as outdated ice cream, molasses,milk by products, and others that include proteins, fat, and water orproteins without fat such as blood could be appropriately substituted.

In example embodiments, a pH of the acidic digest medium 112 is adjustedby a measured addition of the acid or acids 114A. One such acid may bephosphoric acid, to obtain and, preferably, maintain a level of pHbetween about 2.5 and about 4.0. Using phosphoric acid to effect achange in pH includes the added benefit of adding phosphorous to themedium and, in turn, provides a high phosphorous product which mayenhance the desirability of the additive for animal feed. However, otheracidic solutions may also be efficiently used. For example, lactic acidis one such reasonable alternative. In the case where lactic acid isused, the fermentation process which occurs as a natural consequence ofthe use of lactic acid, (in addition to digestion by other acids) alsoacts to break down the protein waste and lowers the pH at the same time.

In example embodiments, protein waste 216, which may be in the form ofspent hens or other poultry carcasses resulting from natural death orrecent euthanization or some portions thereof, may be ground and theacidic digest medium 112 and the ground protein waste 216 may bethoroughly mixed and re-circulated through a chopper pump 88 to producean acidic protein solubles mixture 184. The acidic protein solublesmixture 184 may be maintained at or heated to a temperature optimal foracidic digestive action which may range between about 90 degreesFahrenheit and about 120 degrees Fahrenheit and may be recirculatedperiodically until the mixture is mostly liquid. The heat created by theexothermic digestive process and the friction of recirculation incertain conditions may be enough to maintain the optimal temperatureand, if not, additional heat may be provided. For example, the mixture184 may be recirculated for 1 hour every 12 hours for 3-4 days, however,the speed of the process may be increased. Further, the speed of theprocess is affected by the nature and content of the protein solublesmixture 184 and may be dramatically shortened. For example, in oneembodiment, digestion may be complete in as little as about 30 minutesto about 1½ hours. In example embodiments, the protein solubles mixture184 may be strained and when the number of quills remaining in thestrainer is acceptable, the digestion is complete. In exampleembodiments, the protein solubles mixture 184 may be emulsified 106 toproduce a first emulsified product 100A, and then subjected to a heatshock step 102. The heat shock step 102 may include reachingtemperatures of about 160 F for a short time for example, a few minutesto 30 minutes to an hour. The emulsified and heat shocked mixture 104may be subjected to a second emulsification step 106A, using a smallerplate than used to produce the first emulsified product 100A therebyproducing a second emulsified product 110A. To disperse fats, the secondemulsified product 110A may be allowed to separate. A resulting waterlayer 125 may be drained off and recycled to be re-used for mixing theacidic digest medium 112 and the remaining de-watered emulsifiedproteins 121 may be mixed with a carrier 132. In example embodiments,the resulting water layer 125 may be drained several times before thede-watered emulsified proteins 121 are mixed with a carrier 132.

In example embodiments the carrier 132 may be delivered to a high speedmixer 140 by volumetric feeder 130. The carrier 132 may comprise arelatively high surface area to volume ratio which acts to absorb someof the moisture. Upon mixing with the de-watered emulsified proteins121, a dough like mixture is produced. The dough like mixture may thenbe extruded into a plurality of pellet-like pieces 146 and thepellet-like pieces may be passed through a drying apparatus 126 whichmay use air flow, multiple heat zones, and at least one cooling zone forfurther removal of moisture. The pellet-like pieces may be finally sizedthrough a mill 166 to a uniform, granular size. In example embodimentsthe mill 166 may be a hammer mill. The off-size pellet-like pieces maybe removed and the remaining uniform, granular pellet-like pieces may bepackaged. An apparatus usable to accomplish the foregoing process isdescribed below.

An example of an acidic digest mixing assembly 15 is shown in FIG. 2. Inexample embodiments, the acidic digest mixing assembly 15 may be used tomix acid 114A with, inedible egg 16, and a preservative 18 with water toform the enzymatic digest medium 112 of a given, predetermined, preset,or optimal pH level. The enzymatic digest mixing assembly 15 may includeat least one digest mixing tank 22, pumping means 24, a re-circulatingassembly 26, and means for adjusting the pH level of the acidic digestmedium 12 which, in example embodiments, may be a pH adjustment assembly28. The pumping means 24 of example embodiments may comprise a firstcentrifugal pump and the re-circulating assembly 26 may comprise a firstinductor nozzle 27 associated with the pumping means 24 and a returnpipe 29 for circulating the acidic digest medium 112. In exampleembodiments, the digest mixing assembly 15 may further include loadcells 25 associated with a digital scale 25 a and positioned such thataddition of the acid 114A, preservatives 18, and inedible egg 16 can bemeasured. It is also contemplated that, in addition to externalmeasuring of the ingredients, other internal measurement options suchultrasound and light beams may be used to monitor the amounts of eachingredient as it is added.

The pH adjustment assembly 28 of example embodiments may include a pHprobe 30, a pH monitor 32, and a first positive displacement pump 34 allelectrically associated, and a supply of acidic solution 114A fluidlyconnected to the positive displacement pump 34 and to the digest mixingtank 22 through a check valve 38. The first positive displacement pump34 of example embodiments may include a variable speed motor. In exampleembodiments, the variable speed motor may be configured to pump 1-10gallons per minute. In example embodiments, the acidic digest medium 112may be formed and or placed in the mixing tank 22 and recirculated whilea pH of the acidic digest medium 112 is monitored by the pH monitor 32.For example, the digest medium 112 may be recirculated for at least 3-5minutes while the pH probe 30 provides a pH level to the pH monitor 32.In example embodiments, the pH monitor 32 may compare the pH level withan optimal, preset, predetermined, or given level and send a signal tothe positive displacement pump 34 to move acidic solution 114A into themixing tank 22 where recirculation continues. The re-circulatingassembly 26 may continue to mix the acidic digest medium 112, the pHprobe 30 may again measure the pH level, and the monitor 32 may comparethe level to the optimal, preset, predetermined, or given level, andagain determine whether acid 114A should be added to the mixing tank 22.When the pH level reaches the optimal, preset, predetermined, or givenlevel, the acidic digest medium 112 is ready to be used or stored.

A particular example of the acidic digest medium 112 includes, acid,114A, inedible egg 16 and water. In this example, the pH was lowered tobetween about 2.5 and about 4.0 by addition of phosphoric acid 114A.This pH level is optimal for this particular digest medium, however theamount of acid and the pH may be altered according to the speed ofdigestion desired and the acid used which may, alternatively, be orinclude citric acid, sulfamic acid, or sodium bisulfate.

In example embodiments, once the acidic digest medium 112 has beenprepared, it can either be stored or it can be moved via a transportingdevice 37, such as a tanker truck, to the mobile grinding assembly 40where it may be mixed with ground protein waste 216 for its digestion.Referring now to FIGS. 3 and 4, the mobile grinding assembly 40comprises a movable platform 42 which may include a front portion 43, amid-portion 44 and a rear portion 45, a conveyor belt 56 for movingprotein waste, a holding tank 58 in which the acidic digest medium 12 isstored, at least one prep tank 60, 62, and a pump 64 to move the acidicdigest medium 12 from the holding tank 58 to the at least one prep tank60, 62. In example embodiments, the movable platform 42 may be asemi-trailer. The mobile grinding assembly 40 may further comprise agrinding means 66 which may include a grinder inlet 67 positioned nearthe conveyor belt 56, a grinder plate 68, a grinder outlet 69, and atleast one grinder knife 70, wherein the grinder outlet 69 is positionedsuch that output from the grinder outlet 69 may flow by closedconnection 71 into a hydro pump 82 the hydro pump 82 having a loweroutlet 74. A specific non-limiting example of the grinding means 66 is aWeiler Meat Grinder utilizing a 5 mm or 3 mm plate. However, differentplate combinations may be used such as double-cut, double-knifecombinations with a ¾″ or ⅜″ plate. In this situation, one knife may bepositioned on the inside of the grinder plate 68 and another on theoutside of the grinder plate 68.

The grinding assembly 40 may further comprise a mixing means 80 which,in example embodiments, may comprise at least one second positivedisplacement pump 72, which may be fluidly connected to the at least oneprep tank 60, 62 and to the hydro pump 82 of the grinding means 66 suchthat the acidic digest medium 112 can be moved to the hydro pump 82where output from the grinder outlet 69 is mixed with the digest medium112 to form a protein solubles mixture 184. The acidic digest medium 112may be pumped against the grinder outlet 69 and may wash ground proteinwaste down into the hydro pump 82. The lower outlet 74 of the hydro pump82 is fluidly connected to a centrifugal chopper pump 88 which isfurther associated with the at least one prep tank 60 or 62 and arecirculation piping system 92 including an inductor nozzle 90. Thisarrangement provides a way to move the protein solubles mixture 184through the chopper pump 88 and into the prep tank 60 via the inductornozzle 90 which may be positioned to generate a circular flow in theprep tank 60. The mixture 184 may be continually recirculated throughthe chopper pump 88 until it is of desired consistency and thoroughlymixed. This may require several minutes.

The protein solubles mixture 184 may then transported to the digestingand emulsifying assembly 100, an example of which is shown in FIG. 5,either via pumping it directly or by pumping it first to a tanker truck94 and then to the assembly 100. The mobile grinding assembly 40 may bea closed system wherein the grinder inlet 67 is the only input open tothe environment.

Where more than one prep tank 60, 62 is present, one prep tank 60 may berecirculated or unloaded while another is being filled and recirculated.In this example embodiment, a separate chopper pump may be associatedwith each prep tank.

In example embodiments, the front portion 43 of the movable platform 42may be occupied by a power source 75, for example, a generator, the midportion 44 of the movable platform 42 may be occupied by the holdingtank 58 and prep tanks 60, 62, and the rear portion 45 may be occupiedby the grinding means 66. The conveyor belt 56 may be associated with oroccupy the rear portion 45. In example embodiments, the at least oneprep tank 60, 62 may be a cone-bottomed tank.

The apparatus of example embodiments may further include an electronicload sensor 96, a programmable logical computer circuit 97, a variablefrequency drive 98, and a preservatives pump 99 to deliver preservative18 to the acidic digest medium 112. The load sensor 96 may be located onthe grinding means 66 to sense a load of the grinding means 66. Thevariable frequency drive 98 controls the preservatives pump 99. The loadsensor 96 and variable frequency drive 98 may be connected to theprogrammable logical computer circuit 97. The programmable logicalcomputer circuit 97 may be programmed with a program to determine theamount of preservative to pump based on a load.

In example embodiments, a relationship may be established between theamperage load on the grinding means 66 and the desired revolutions perminute to run the preservatives pump 99. The following program is usablein example embodiments:

Grinder Amp Load Preservative Pump RPM 40 amps no load 0 RPM 50 amps 25%load 437 RPM 60 amps 50% load 875 RPM 70 amps 75% load 1300 RPM 80 ampsFull load 1800 RPM

The digesting and emulsifying assembly 100 of example embodiments may bestationary or mobile or some portions may be mobile, while others arestationary. A non-limiting example of the digesting and emulsifyingassembly 100 is shown in FIGS. 5 and 6. As shown in FIGS. 5 and 6, thedigesting and emulsifying assembly 100 may include a tank 101 fordigesting the protein solubles mixture 184, a means 102 for heating themixture 184, a means 103 for recirculating the mixture 184 for periodicmixing, a means 107 for collecting fats from the digester tank 101, andan emulsifier 105. In example embodiments, the means 103 forrecirculating the mixture 184 may include a centrifugal pump 104. Theemulsifier 105 may be fluidly connected to a pump 106, the digester tank101, and a separator tank 108 (optional).

In example embodiments, the digester tank 101 may be a non-pressure tankwith a cone bottom 109 enclosed within a housing 110. The heating means102 of example embodiments may include a heating element 111 and water(not shown) enclosed in the housing 110. The housing 110 of exampleembodiments may be a vented water jacket. The heating element 111 ofexample embodiments may heat the water in the housing. The proteinsolubles mixtures 184 may be recirculated while it digests. In certainconditions friction from circulation and the exothermic digestion mayprovide heat sufficient to maintain the digest medium at an optimaltemperature and reduce or negate the need for additional heat.

In example embodiments, acid 114A may be stored in the acid storage tank112 and pumped into recirculation means 103 by the positive displacementpump 113 while the protein solubles 184 are recirculated. Alternatively,the acid 114A could be pumped solely by the centrifugal pump 104. A pHprobe in the digest tank 101 may control the pump 113 and/or thecentrifugal pump 104 to stop the pumps at a desired pH level.

Because acid 114A may be introduced into the protein solubles 184, thepH of the protein solubles 184 may drop causing fat (not shown) tosettle out of the digest tank 101. The settled fat may be pumped out ofthe digester tank 101 using the centrifugal pump 104. The recirculationmeans 103 includes a recirculation valve 115 and a closable connection116 connecting the digest tank 101 to the first fat storage tank 117.During recirculation, the recirculation valve 115 is open and thecloseable connection 116 is closed. During collection of fat therecirculation valve 115 is closed and the closeable connection 116 isopen. In example embodiments the centrifugal pump 104 may stop pumpingfat when all of the fat in the digester tank 101 has been removed asconfirmed by visual operation.

The centrifuge 118 may be fluidly connected to the first storage tank117 and the second fat storage tank 119. The centrifuge 118 may act topump the fat from the first storage tank 117 and separate water fromfat. The separated water (not shown) may be recirculated back into theprotein solubles mixture 184 and water may be recycled in exampleembodiments. Separated fats may be stored in the second storage tank119. The stored fats may be used as a fuel source for the drying system120 or for other purposes.

After digestion and removal of fat, the protein soluble mixture 184 maybe pumped into the emulsifier 105 for further removal of fats. Afterdigestion of the protein solubles mixture 184 in the digest tank 101,the fat (not shown) may be emulsified 206 with the protein solubles 184to form a first emulsification product 200A. Thereafter, the firstemulsification product 200A may be heated quickly to between about 90 Fand about 120° F., for a short time of at least about 5 minutes, aperiod of between about 5 minutes and 60 minutes, or up to 90 minutes,as a heat shock step 202A. The heat shocked, first emulsificationproduct 204A may be stored until use. Alternatively, the heat shocked,first emulsification product 204A may be subjected to a secondemulsification step 206A (either immediately or after a period ofstorage) forming a second emulsification product 210A which may then beemployed as an animal food product. Emulsification produces the firstemulsification product 204A which may be transferred to a separator tank108. The separator tank 108 may have a closeable opening 123 in fluidconnection with the enzymatic digest mixing tank 22. A water layer 125may form in the separator tank 108 and the water layer 125 may bedrained for use in mixing additional digest medium 12.

Referring to FIGS. 7 and 8, the first emulsified product 204A and thesecond emulsified product 210A may be moved to the drying system 120which may include a dough mixing apparatus 122, an extruder 124 and adrying apparatus 126. An example of the dough mixing apparatus 122 isshown in FIG. 7. As shown in FIG. 7, the dough mixing apparatus 122 maycomprise a volumetric feeder 130 for measuring an absorbing carrier 132which may be mixed with the emulsified product 204A or 210A. In exampleembodiments, the dough mixing apparatus 122 may be positioned over amill 134 for finely grinding the absorbing carrier 132. The mill 134may, for example, be a high speed hammer mill or disc mill. The doughmixing apparatus may further include a second conveyor belt 136 whichmay move the absorbing carrier 132 from the mill 134 to a high speedcontinuous mixer 140. A third positive displacement pump 142 may beassociated with the separator tank 108 and may move the emulsifiedproteins 210A, 204A to the high speed mixer 140 where it may be mixedwith the absorbing carrier 132 to produce a dough like mixture. Inexample embodiments, the absorbing carrier 132 may be a substance withcharacteristics like wheat mids, soybean meal, corn, or a previouslydried material made for such purpose and the third positive displacementpump 142 may be of the variable speed variety.

In example embodiments, the dough like mixture may be moved to theextruder 124 which may pressure-force moisture out and produce aplurality of pellet-like pieces 146. In example embodiments thepellet-like pieces may have a thickness of about 3/16″ and of randomlength. The pellet-like pieces 146 may be extruded onto an oscillatingbelt 148 which may distribute the pellet-like pieces 146 evenly andconnect the extruder 124 to the drying apparatus 126. Additionalmoisture may be removed by the drying apparatus 126 using heat and airmovement. An example of the drying apparatus 126, as shown best in FIG.8, may comprise a dryer bed 150 positioned to receive the pellet-likepieces 146 from the oscillating belt 148, a housing 152 through which adryer bed conveyor belt 154 may move and convey the pellet-like pieces146 and which may include at least one heating zone 156, 158, 160, atleast one cooling zone 162, and means to direct airflow 164. The mill166 may receive the pellet-like pieces 146 after they emerge from thehousing 152 and size the plurality of pellet-like pieces 146 to auniform size. A vibrating screen 170 may be used to remove any of theplurality of the pellet-like pieces 146 which are of a non-uniform size.In example embodiments, the means to direct airflow 164 may comprisefans positioned to alternate the flow of air to provide uniformity indrying. In example embodiments, the heat zones 156, 158, 160 may providetemperatures of 300, 275, and 250 Fahrenheit, in this order, such thatthe maximum temperature of the plurality of pellet-like pieces does notexceed 250 Fahrenheit. If the heat of the pellet-like pieces 146 exceedsthis level their taste may be too bitter and the amino acids may bedegraded. The cool zone 162 may return the pellet-like pieces 146 towithin about 10 degrees of ambient temperature. Vents may return theheated air from the cool zone 162 to the heat zones.

The protein solubles mixture 184 may alternatively be digested throughfermentation. In this example embodiment, the pH of the enzymatic digestmedium 12 may be adjusted using lactic acid. The fermentation itselfreplaces the enzymatic digest and a fermentation assembly 200 replacesthe digest and emulsification assembly 100. The fermentation assembly200 may include a non-vented low pressure tank 202, a means 264 forrecirculating protein solubles 184, and a means 206 for collecting gas.

In example embodiments, the fermentation tank 202 may have a means 208for heating the mixture 184 comprising a cone bottom 210 surrounded by ahousing 212 filled with water (not shown) and heated by a heatingelement 214. The heated water in turn heats the protein solubles mixture184 and microorganisms (not shown) within the tank 202. Themicroorganisms in the tank 202 may be bacteria that produce methane gas.In example embodiments, the recirculation means 264 may include acentrifugal pump 216 that may recirculate the contents of the tank 202.In example embodiments, the gas collection means 206 may comprise piping218 in fluid connection with the tank 202, a compressor 220, and apressure tank 222. During recirculation, the bacteria may produce gas(not shown) and may increase pressure in the tank 202. In exampleembodiments, the tank 202 may include a pressure sensor 224 to monitorpressure in the tank 202. At the appropriate pressure, the pressuresensor 224 may activate the compressor 220 which may compress the gasfor storage in the pressure tank 222. As a safety measure, the pressuretank 222 may include a pressure gauge 226. To prevent backflow of gas,the piping 218 may include check valves 228 located before and after thecompressor 220. The stored methane gas may be used as a fuel source forthe dryer system 120 or for other purposes. After digestion andcollection of gas, the protein soluble mixture 84 may be pumped into theemulsifier 105 for further removal of fats consistent with the earlierdescribed example digest and emulsification assembly 100.

Example embodiments provide a process to treat animal byproducts such ascarcasses including poultry carcasses or only portions of carcasses. Forexample, some embodiments provide a method to treat blood and featherswhich are waste products of a poultry processing plant, and to treatthis mixture on site at least to the degree necessary to avoid bacterialcontamination and reduce other negative effects of a rendering plant.The method reduces or minimizes problems associated with odor andbacteria, such as salmonella and E. coli. Embodiments also provide amethod of treating byproducts in a manner that is sanitary. The variousembodiments will provide a product that is a high protein material. Oneuse of the high protein material is as an additive to existing animalfoods and/or as a new ingredient for animal foods. For example, the highprotein material may be added to a feed additive.

In example embodiments, blood and feathers, and optionally offal, necks,backs and/or wings, may be collected on site of a rendering plant or aslaughter plant. These products may be collected into stationary ormobile tanks. In example embodiments, the blood may be combined withenzymes and preservatives to form an enzymatic digest medium; in anotherembodiment, an acidic digest medium will be formed. The enzymatic digestmedium or acidic digest medium, in turn, may be combined with thefeathers, and optionally offal and/or other parts remaining. Preferablythe feathers are ground prior to addition to the medium which willdecrease the time necessary to achieve the degree of digestion required.The enzymes in the enzymatic digest medium will liquefy substantiallyall of the feathers (and offal, if present) and the progress of thedigestion can be monitored by checking the level of quills remaining.Once the number of quills or quill parts is at the desired level, thedigestion process may be allowed to end by removing the heat supply, oradjusting the pH or by other known means. The digested mixture resultingeither from acidic or enzymatic digestion of the present invention maybe stored for a relatively long period of time. It may be used in itsliquid state or dried using heat, and thereafter milled in the presenceof cereal that operates as a carrier or combined with another materialprior to or during drying.

Where offal is included in the digest medium, or added to the digestmedium at a later time, fat will be present. The fat may be separated asdescribed herein, and the remaining portion be emulsified, with dryingof the material to follow.

In example embodiments, the processes may occur in a mobile or astationary system. The digest equipment may include a tank for producingthe digest medium and another tank for the actual digestion process. Thesecond tank may be equipped with a means to stir the digest and theanimal byproducts and a means to pump the material out when digestion isfinished. The first and second tanks may be configured with a heatingsystem to heat the mixture of the animal byproducts and the enzymatic oracidic digest medium while the mixture is mixing.

FIG. 10 is a view of a digest mixing assembly 15′ in accordance withexample embodiments which may be employed to create either enzymatic oracidic digest mediums of the present invention. In example embodiments,the digest mixing assembly 15′ of FIG. 10 is similar to the exampledigest mixing assembly 15 of FIG. 2. For example, as shown in FIG. 10,the digest mixing assembly 15′ may include a digest tank 22′ which maybe configured to receive a preservative 18′, at least one enzyme 14′ oracid 114A, an organic material 16′, and water. In example embodiments,the preservative 18′, the at least one enzyme 14′ or acid 114A, theorganic material 16′, and the water may be mixed in the digest tank 22′to form a digest medium 12′. In example embodiments, a moisture contentof the digest medium 12′ or 112 may be about 65% or greater to renderthe digest medium 12′ or 112 usable for digesting animal byproducts (forexample, feathers, to be explained later).

In example embodiments the organic material 16′ may be blood, forexample, avian blood such as chicken or turkey blood. The at least oneenzyme 14′ may be a protease, a lipase, a keratinase, an amylase, or acombination thereof. The at least one acid 114A may comprise phosphoricacid, sulfamic acid, citric acid, sodium bisulfate or other acidscapable of providing the desired pH range. Thus, the at least one enzyme14′ or at least one acid 114A may be capable of breaking down proteinsor fats that may be present in the digest medium 12′ or proteins or fatsthat may be combined with the digest medium 112 or 12′. For example, thedigest medium 12′ or 112 may be combined with feathers either during theproduction of the enzymatic digest medium 12′ or 112 or added to theenzymatic digest medium 12′ or 112 at a later time.

In example embodiments, the preservative 18′ may be a preservative or anagent that prevents or reduces microbial growth. For example,non-limiting examples of the preservative 18′ are sodium bisulfate,meta-bisulfate, a reducing agent, potassium sorbate, sodium sulfate,phosphoric acid, and hydrochloric acid. The proper selection of apreservative or a combination of preservatives depends on the materialsto be digested and the enzyme digests itself. In example embodiments,the enzyme digest medium 12′ or acidic digest medium 112 may be stablystored for a long period of time due to the presence of a preservative18′. For example, the digest medium 12′ or 112 may be stored for severalmonths prior to its use.

In example embodiments, the digest mixing tank 22′ may be furtherconfigured to receive a pH controlling medium 36′. In exampleembodiments, the pH controlling medium 36′ may be a basic medium or anacidic medium. For example, non-limiting examples of the pH controllingmedium 36′ may be sodium hydroxide or phosphoric acid. The addition ofthe pH controlling medium 36′ may be helpful in regulating a pH of theenzyme digest medium 12′. In example embodiments, the pH controllingmedium 36′ may be added to the enzymatic digest mixing tank 22′ by a pHadjustment assembly 28′ which may be comprised of a pump 34′, a pHmonitor 32′, and a pH probe 30′. In example embodiments, the pH probe30′ may be exposed on an inside of the digest tank 22′ (whetherenzymatic or acidic digest) and thus may be exposed to the enzymatic oracidic digest medium.

In example embodiments, the pH probe 30′, the pH monitor 32′, and thefirst positive displacement pump 34′ may be electrically associated, anda supply of pH controlling medium 36′ may be fluidly connected to thepositive displacement pump 34′ and to the enzymatic digest mixing tank22′ through a check valve 38′.

The first positive displacement pump 34′ of example embodiments mayinclude a variable speed motor. In example embodiments, the variablespeed motor may be configured to pump 1-10 gallons per minute. Inexample embodiments, the digest medium 12′ or 112 may be formed orplaced in the mixing tank 22′ and recirculated while a pH of the digestmedium 12′ or 112 is monitored by the pH monitor 32′. For example, thedigest medium 12′ or 112 may be recirculated for at least 3-5 minuteswhile the pH probe 30′ provides a pH level to the pH monitor 32′. Inexample embodiments, the pH monitor 32′ may compare the pH level of thedigest medium with a predetermined, preset, or optimal pH level and senda signal to the positive displacement pump 34′ to move the pHcontrolling medium 36′ into the mixing tank 22′ where recirculationcontinues. The re-circulating assembly 26′ may continue to mix thedigest medium, the pH probe 30′ may again measure the pH level, and themonitor 32′ may compare the pH level to the predetermined, preset, oroptimal pH level and again determine whether the pH controlling medium36′ should be added to the mixing tank 22. When the pH level reaches thepredetermined, preset, or optimal pH level, the digest medium ′12 or 112is ready to be used or stored.

In example embodiments, the digest mixing assembly may be used to mixthe at least one enzyme 14′ or acid 114, the preservative orpreservatives 18′, the organic material 16′, and water. The digestmixing assembly 15′ may also be usable for mixing the pH controllingmedium 36′ with the enzymes 14′ or acid 114, the preservative 18′, theorganic material 16′, and the water to form the digest medium 12′ or 112of a predetermined, preset, or optimal pH level. For example, theenzymatic digest mixing assembly 15′ may produce an enzymatic digestmedium 12′ having a pH of about 7. In example embodiments, the enzymaticdigest mixing assembly 15′ may include a pump 24′ and a re-circulatingassembly 26′. The pump 24′ of example embodiments may comprise a firstcentrifugal pump and the re-circulating assembly 26′ may comprise afirst inductor nozzle 27′ associated with the pump 24′ and a return pipe29′ for circulating the digest medium. In example embodiments, the pump24′ may alternatively be another type of pump, for example, a chopperpump.

In example embodiments, the enzymatic digest mixing assembly 15′ mayfurther include load cells 25′ associated with a digital scale 25 a′ andpositioned such that addition of the at least one enzyme 14′ or acid114, preservatives 18′, and organic material 16′ can be measured. It isalso contemplated that, in addition to external measuring of theingredients, other internal measurement options such ultrasound andlight beams may be used to monitor the amounts of each ingredient as itis added.

In example embodiments, the digest mixing assembly 15′ may be astationary structure. For example, the digest mixing assembly 15′ may bea stationary structure used at a slaughter house. In this case, theorganic material 16′ may be blood, for example, avian blood, and theblood may be transferred to the mixing tank 22′. In this particularnonlimiting example embodiment, the avian blood produced as part of aslaughter operation may be mixed with the at least one enzyme 14′ oracid 114 and the preservative or preservatives 18 in the digest mixingtank 22′. Due to the presence of the preservative 18, the mixture of theblood, the enzymes 14′ or acids 114, and the preservative 18′ may bestored for a relatively long period of time. Thus, the digest medium 12′or 112 may be stored in the mixing tank 22′ for an indefinite period oftime or may be pumped to a holding tank for an indefinite period oftime. In example embodiments, a pH of the digest medium 12′ or 112 maybe controlled via the pH adjustment assembly 28′. For example, the pH ofthe digest medium 12′ or 112 may be controlled to be around 7.

In example embodiments, the mixing tank 22′ may be transportable andthus may be moved from one facility to another facility. In thealternative, the digest medium 12′ or 112 may be pumped from the mixingtank 22′ to a holding tank which may be loaded on a truck. Exampleembodiments, however, are not limited thereto. For example, the entiredigest mixing assembly 15′ may be truck mounted. Thus, the entire digestmixing assembly 15′ may be mobile.

In example embodiments, the digest medium 12′ or 112 may be usable fordigesting proteins, for example, proteins from feathers. For example, anavian slaughtering operation may produce by products such as blood,offal, and feathers. The blood may be used as the organic material 16′in producing the medium 12′ or 112. At least one of the feathers andoffal may be collected, ground, and added to the digest medium 12′ or112 either during a production of the digest medium or afterwards.

FIG. 11 is a view of a mixing system 80′ that may be usable for mixinganimal products, for example, feathers and/or offal, with the digestmedium 12′ or 112. The mixing system 80′ may be substantially the sameas the mixing system 80 illustrated in FIG. 4. For example, the mixingsystem 80′ may comprise at least one second positive displacement pump72′, which may be fluidly connected to the at least one prep tank 60′,62′ and to the hydro pump 82′ such that the digest medium 12′ or 12 canbe moved to a hydro pump 82′ where output from the grinder outlet 69′ ismixed with the digest medium to form a protein solubles mixture 84′. Thedigest medium may be pumped against the grinder outlet 69′ and may washground protein waste down into the hydro pump 82′. The lower outlet 74′of the hydro pump 82′ may be fluidly connected to a centrifugal chopperpump 88′ which may be further associated with the at least one prep tank60′, 62′ and a recirculation piping system 92′ including an inductornozzle 90′. This arrangement provides a way to move the protein solublesmixture 84′ through a chopper pump 88′ and into the at least one preptank 60′, 62′ via the inductor nozzle 90′. The system may be arranged togenerate a circular flow in the at least one prep tank 60′, 62′. Themixture 84′ may be continually recirculated through the chopper pump 88′until it is of desired consistency and thoroughly mixed. This mayrequire several minutes, for example, sixty (60) minutes.

In example embodiments, animal byproducts, such as feathers and offal,may be ground by grinding means 66′ which may be substantially the sameas the grinding means 66. As in the previous non-limiting exampleembodiments, the animal by products, for example, the feathers and/oroffal, may mix with the digest medium 12′ in a closed connection 71′which may be substantially the same as the closed connection 71

In example embodiments, the at least one prep tank 60′, 62′ may be ajacketed prep tank that may be heated by injecting steam into thejacket. For example, the at least one prep tank 60′, 62′ may be aconventional cone bottomed tank. Thus, the at least one prep tank 60′,62′ may be heated during the mixing process. For example, the at leastone prep tank 60′, 62′ may be heated such that a temperature of themixture 84′ is heated to about 110° F. or to a range up to about 125° F.or below.

In example embodiments, the at least one prep tank 60′, 62′ may be atruck mounted or may be part of a fixed structure. Thus, the at leastone prep tank 60′, 62′ may be stationary or mobile.

In example embodiments, after the mixture 84′ of the animal product andthe digest medium 12′ or 112 has been thoroughly mixed in the at leastone prep tank 60′, 62′ and the animal byproducts have been properlyliquefied by the digest medium the mixture 84′ may be sent to a dryer,for example, a drum dryer, a conveyor dryer, a spray dryer, or a fluidbed dryer, which may be used to dry the mixture 84′.

In example embodiments, when only feathers are used as the animalbyproducts, the enzymatic digest medium 12′ may only contain keritinaseand the enzymatic digest medium 12′ may be controlled to have a pH ofbetween about 6 and about 8, for example, about 7. Alternatively, theacidic digest medium 112 may comprise a pH between about 2.5 and about4. In addition, when only feathers are used as the animal byproducts,the mixture 84′ may be thoroughly digested provided it is mixed for atime, for example, greater than about twenty minutes up to about 1½hours, at a temperature of about 100 F to a temperature at or belowabout 125 F. Applicants have found that a mixture of one part blood andpreservative to about two parts feathers is acceptable for producing amixture 84′ which is thoroughly digested within about an hour. In thisparticular embodiment, because feathers contain relatively little fat,the mixture 84′ may be dried in the dryer without a need to remove fattherefrom.

In example embodiments, the mixture 84′ may be stored for a relativelylong time. For example, the mixture 84′ may be stored for severalmonths. In addition, because the mixture 84′ is substantially liquid,the mixture 84′ may be pumped from the at least one prep tank 60′ and62′ to a holding tank. The holding tank may be a stationary structure.In the alternative, the holding tank may be movable by a truck. Thus,the mixture 84′ may be moved from one location to another location.Because the mixture 84′ may be moved, a location of a dryer may vary.For example, the dryer may be at a slaughterhouse. In the alternative,the dryer may be located at a site which is remote from theslaughterhouse. In example embodiments, the dryer may be located betweenslaughterhouses. For example, if a certain region includes twoslaughterhouses separated by fifty miles, the dryer may be locatedbetween to the two slaughterhouses, for example, twenty five miles fromeach slaughterhouse.

In example embodiments, when only feathers and offal are used as theanimal byproducts, the digest medium 12′ or 112 may comprise keritinase,protease, lipase, phosphoric acid, other acid, or some combinationthereof and may be mixed to have a pH of about 7 or, for an acidicmedium pH between about 2 and about 4. In addition, when only feathersand offal are used as the digested protein, the mixture 84′ or 184 maybe thoroughly digested in about fifteen minutes to about one hourprovided it is mixed at a temperature of about 110 F to about 120 F andnot above about 125 F. Applicants have found that a mixture of one partblood and preservative to about two parts feathers and offal isacceptable for producing the mixture 84′ which may be digested withinabout an hour. In this particular embodiment, because feathers and offalcontain relatively little fat, the substantially liquefied mixture 84′or 184 may be dried in the dryer without a need to remove fat therefrom,however, the fat may optionally be separated prior to drying theremaining substantially liquefied mixture.

Example embodiments are not limited to treating only feather and offal.For example, the apparatus of example embodiments may also be usable fordigesting other animal byproducts such as heads, feet, necks, and backsof poultry carcasses along with blood and offal or without offal. As inthe earlier explained embodiments, at least one of the feet, necks, andbacks may be fed into the grinding means 66′ and then mixed with thedigest medium 12′ or 112 in the at least one prep tank 60′ and 62′. Forexample, the ground heads, feet, neck, and backs may be mixed with thedigest medium 12′ or 112 for greater than about twenty minutes (forexample, about one hour) at a temperature between 100 F and 120 F and apH of between about 6 and about 8, for example, about 7 or, for theacidic digest medium, pH between about 2 and about 4. In exampleembodiments, the digest medium 12′ may include at least one of lipase,protease, and amylase, phosphoric acid, and other acids to digest atleast one of the ground heads, feet, neck and backs.

As shown at FIG. 4, or 5, or 11, the animal byproducts may be ground bygrinding means 66 or 66′ to include a carrier comprising any one or moreof phosphoric acid, yeast, and/or preservative materials which mayinclude potassium sorbate and antioxidants. The ground byproduct andpreservative(s) may be acidified to pH between about 2.5 and 4.0 andmaintained or heated to 90-120 F to form a stable acidic digest medium.Acidification may employ sodium bisulfite, sodium bisulfate, and/orphosphoric acid. However, although sodium bisulfite would functionallysuffice, it may not be appropriate for use in a final product comprisingfood for felines; it scavenges B vitamins which are crucial to felinediets. Further, it has a tendency to pickle the product and reducesenzyme activity a bit. While an alternative to phosphoric acid or sodiumbisulfate, it is a less favored alternative for the reasons statedherein. The stable acidic digest medium preferably exhibits stabilityfor up to about 25 days. Addition of a proteinaceous material to thestable acidic digest medium 112 results in a protein solubles mixture184. The protein solubles mixture 184 may be emulsified; the proteinsoluble mixture 184 may be emulsified and then heat shocked to about 160F to form a first emulsified product 100A and thereafter stored. Theprotein solubles mixture 184 may be emulsified in a firstemulsification, heat shocked, and then emulsified again in a secondemulsification to form a second emulsified product 110A of generallyhomogenous particle size. The product 100A or 110A may be dewatered toform a dewatered emulsified protein 121. Alternatively, the dewateredemulsified protein 121 may be mixed with a carrier 132 to form yetanother product 121A. The products 100A, 110A, 121A resulting from thestable acidic digest may be used as animal foods.

Thus, example embodiments have been described in an illustrative manner.It is to be understood that the terminology that has been used isintended to be in the nature of words of description rather than oflimitation.

Many modifications and variations of example embodiments are possible inlight of the above teachings. For example, it may be possible for allparts of the system to be made in mobile form or for none of the systemto be mobile. Many different pumps are available and may be usedaccording to need. The enzymatic digest medium and the acidic digestmediums can be altered to accommodate different protein/bone/feathercombinations. Therefore, within the scope of the appended claims, theinventor so defines his invention.

What I claim is:
 1. A process for making a product for animalconsumption, said process comprising: a) grinding a protein source andadding acid to the ground protein source to generate an acidic digestmedium exhibiting biological stability at ambient temperatures up to atleast 21 days, b) mixing a portion of the acidic digest medium with anadditional amount of ground protein to form an acidic mixture, c)emulsifying the acidic mixture to form an acidic digest product saidacidic digest product exhibiting biological stability at ambienttemperatures up to at least 21 days.
 2. The process of claim 1 furthercomprising optionally subjecting the acidic digest product to a heatshock step to retard bacterial growth prior to storing.
 3. The processof claim 2, further comprising a second emulsifying step comprisingemulsifying the acidic digest product.
 4. The process of claim 3, saidsecond emulsifying step following the heat shock step.
 5. A process formaking a product for animal consumption, said process comprising mixingan acid with a ground protein source to form an acidic digest medium,said acidic digest medium capable of maintaining its biologicalstability for up to 90 days.
 6. The process of claim 5 furthercomprising adding an additional protein source to the acidic digestmedium and emulsifying the resulting acidic mixture to form an acidicdigest product followed by heat shocking the acidic digest productresulting in enhanced biological stability.
 7. The acidic digest mediumof claim 1, said acidic digest medium comprising pH between about 2.5and 4.5.
 8. The acidic digest medium of claim 2 wherein said acidconsists of phosphoric acid.
 9. The acidic digest medium of claim 2wherein said acid is selected from a group consisting of: phosphoricacid, sulfamic acid, citric acid, and sodium bisulfate.
 10. The processof claim 6 wherein said additional protein sources comprises spent hens.11. The process of claim 6, said acidic digest product exhibitingbiological stability for up to 90 days.
 12. The process of claim 6, saidacidic digest medium exhibiting biological stability for up to 21 days.13. The process of claim 6, said acidic digest medium exhibitingbiological stability for up to 90 days.
 14. A process for making aproduct for animal consumption, said process comprising: a) Grinding aprotein source with a carrier; b) Acidifying the ground protein/carrierproduct at a temperature between about 90 and about 120 degreesFahrenheit; c) Mincing and maintaining the temperature of the acidifiedground protein/carrier product between about 90 and about 120 degreesFahrenheit at pH between about 2.5 and about 4.0 and allowing saidground protein to mostly liquefy to form an acidic digest mediumexhibiting biological stability in a sealed container for at least 21days.
 15. The process of claim 14, further comprising mixing an amountof the acidic digest medium with an additional protein source to form anacidic mixture, followed by a heat shock, and emulsification.
 16. Theprocess of claim 15 further including a drying step afteremulsification.
 17. A product for animal consumption, said product madeby a process comprising acidifying ground protein to form a digestmedium of pH between about 2.5 and 4.5 and exhibiting biologicalstability for up to 21 days, emulsifying the digest medium withadditional protein and heat shocking to form the product.
 18. Theproduct of claim 17 wherein the additional protein and the digest mediumare combined and the additional protein allowed to be at least partiallyliquefied prior to heat shocking thereafter employing a secondemulsification step to form the product.
 19. A process for making aproduct for animal consumption, said process comprising acidifying aground protein to pH 2.5 to pH 4.0 to form a digest medium havingbiological stability at ambient temperatures for at least 21 days and upto 90 days.
 20. The process of claim 19 further comprising combining thedigest medium with additional protein to form an acidic mixture,emulsifying the acidic mixture and subjecting to a heat shock stepcomprising about 160 F to form a product stable for up to 25 days attemperatures up to about 120 F.
 21. The process of claim 20, said groundprotein consisting almost completely of ground poultry including:feathers, heads, feet, entrails, undeveloped eggs, blood, carcassportions.
 22. The process of claim 6 wherein heating the emulsified,acidified ground protein comprises a heat shock of about 160 degrees F.23. The process of claim 8 further comprising a second emulsificationsaid second emulsification after the heat shock.
 24. A process formaking a product for animal consumption, said process comprising thesteps of: a) acidifying a first amount of ground protein to form anacidic digest; b) adding additional protein and emulsifying to form anacidic digest product; c) heat shocking the acidic digest product toabout 160 degrees; d) emulsifying the heat shocked, acidic digestproduct to form a product for animal consumption exhibiting biologicalstability for up to 21 days at ambient temperatures. e) The process ofclaim 10, wherein exhibiting biological stability comprises up to 90days.